Megaloblastic anemia is a subcategory of macrocytic anemia, referring to macrocytosis (abnormally large red blood cells) in the presence of anemia. Vitamin B12 and folate deficiencies most commonly contribute to megaloblastic anemia by affecting DNA synthesis and red blood cell (RBC) formation. Consequently, abnormally large RBCs called megaloblasts develop in the bone marrow. Macrocytosis affects 2-4% of the general population, and 60% of people with macrocytosis have anemia. Due to wide variation in contributing factors across populations, data regarding the prevalence of megaloblastic anemia is mixed. It is, however, generally accepted that folate deficiency is a common cause of megaloblastic anemia after vitamin B12 deficiency. (5, 6)
This article will focus on folate deficiency anemia: what may contribute to it, how to recognize it through physical exam and laboratory findings, and how to implement a holistic approach for supporting health.
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What is Folate Deficiency Anemia?
Vitamin B9 is a water-soluble vitamin found naturally in foods as folate and in supplements as its synthetic form called folic acid. The body utilizes folate for the synthesis of DNA, the development of the nervous system, and the maturation of red blood cells. When deficient, these folate-dependent pathways may be compromised, and one of the consequences is folate deficiency anemia. (2)
Folate deficiency anemia is a type of megaloblastic anemia resulting from impaired DNA synthesis and RBC maturation. Large RBCs, called megaloblasts, are formed in the bone marrow and circulate through the body in smaller concentrations than usual. Not only does the rate of RBC synthesis decrease in folate deficiency, but megaloblasts also have shorter lifespans compared to healthy RBCs. Both of these factors may contribute to the development of anemia. (3)
The most common reasons for folate deficiency may include (9):
- Inadequate intake in those with restricted diets, disordered eating habits, and alcohol use disorder
- Increased demand due to pregnancy and lactation
- Impaired absorption due to gastrointestinal conditions like Celiac disease, inflammatory bowel disease (IBD), atrophic gastritis, hypochlorhydria, and bowel resection
Some medications are also known to affect folate levels. These include acid reducers (i.e., proton pump inhibitors, histamine H2 antagonists, and antacids), antipsychotics, anticonvulsants, oral contraceptives, metformin, and methotrexate. (9)
Folate Deficiency Anemia Symptoms
Anemia associated with folate deficiency presents with general and vague symptoms. Symptoms may appear gradually and generally tend to become more noticeable as the degree of anemia and deficiency increases. Common anemia symptoms may include (3):
- Cold extremities
- Dizziness
- Fatigue
- Headaches
- Irregular heart rate
- Pale skin
- Shortness of breath
- Weakness
Additionally, you may also experience symptoms that could be related to folate deficiency (1):
- Angular Cheilitis: inflammation and cracking of the corners of the mouth
- Changes in skin, hair, and fingernails
- Cognitive impairment: difficult concentration, memory loss, confusion
- Depression
- Diarrhea
- Glossitis: inflamed tongue with ulcerations
Complications Of Folate Deficiency Anemia
Unresolved anemia is associated with chronic fatigue and heart problems, as the heart must compensate for the lack of oxygen in the blood; this can lead to irregular heartbeat, enlargement of the heart, and in some cases, heart failure (3).
There are associated health risks with folate deficiency, too. Insufficient maternal folate status during pregnancy is associated with an increased risk of neural tube disorders, low infant birth weight, preterm delivery, and fetal growth restriction (2). Neuropsychiatric complications, including depression, insomnia, cognitive decline, and psychosis, are linked to folate deficiency (1).
Functional Medicine Labs to Diagnose Folate Deficiency Anemia
A complete blood count (CBC) is a panel of many biomarkers related to the various types of blood cells. The table below details CBC findings correlated with macrocytic anemia:
A blood smear, which evaluates blood cells under a microscope, is often ordered in conjunction with a CBC. Oval-shaped, enlarged RBCs and hypersegmented neutrophils are key findings of megaloblastic anemia. (6)
A reticulocyte count may also help to differentiate between causes of anemia. Reticulocytes are immature RBCs and may be measured in abnormal quantities in certain types of anemias. Reticulocytes are usually normal or low in folate deficiency anemia.
Findings of macrocytic anemia should prompt additional testing to differentiate between folate and B12 deficiency. Serum folate and vitamin B12 levels should be measured to differentiate between the anemia's cause. A serum folate level of less than 3 mcg/L suggests folate deficiency. (7)
RBC folate is a more accurate representation of folate stores. Consider ordering RBC folate for patients who have recently changed their folate intake or for those in whom you have a strong clinical suspicion of folate deficiency despite normal serum folate levels. RBC folate less than 150 mcg/L is consistent with folate deficiency. (7, 8)
Elevated homocysteine is suggestive of folate deficiency but is also elevated in vitamin B12 deficiency and kidney disease. (7)
Methylmalonic acid (MMA) can help differentiate between folate and vitamin B12 deficiency because MMA levels rise in the presence of vitamin B12 deficiency but not in folate deficiency.
Tests to Rule Out Causes of Folate Deficiency
Once folate deficiency anemia is identified, the underlying cause of folate deficiency should be explored. Tests to help in this process include:
- Quantitative serum hCG to rule out pregnancy
- Celiac panel
- Elevated fecal calprotectin and lactoferrin and serum C-reactive protein (CRP) help support a diagnosis of IBD
- The AUDIT and CAGE questionnaires can help to screen for alcohol use. A liver panel can also help identify liver function patterns that may suggest chronic alcohol consumption.
Endoscopy and colonoscopy are the preferred diagnostic imaging methods to explore suspected Celiac disease and IBD that may affect folate absorption.
Methylenetetrahydrofolate reductase (MTHFR) is an enzyme responsible for methylating and activating folate in the body. Genetic variations in the MTHFR gene coding for this enzyme can decrease enzyme activity. Knowing your MTHFR genotype can be clinically valuable when addressing folate deficiency.
Functional Medicine Approach for Folate Deficiency Anemia
Folate deficiency anemia is addressed by supporting folate levels. While this is accomplished in the short-term by utilizing folate-rich foods and folic acid supplements, the long-term maintenance of folate status and prevention of deficiency recurrence relies on addressing the factors contributing to deficiency.
Nutrition
Folate is the naturally occurring form of vitamin B9 found in various foods, including green vegetables, legumes, and liver. In 1998, the FDA began requiring that cereals and grains be fortified with folic acid to help prevent folic acid deficiency-related complications; since then, these foods have been large contributors of folic acid in the standard American diet. (2)
The daily value (DV) of folate is dependent on age. The DV for adult men and women is 400 mcg of dietary folate equivalents (DFE) daily. The DV increases to 600 and 500 mcg DFE daily during pregnancy and lactation. If you are not meeting recommended dietary intakes through diet alone, folic acid supplementation may be considered.
Reducing alcohol consumption may support folate status by improving the body's absorption, storage, and excretion of the vitamin.
Herbs & Supplements
Folic acid is the bioavailable synthetic derivative of vitamin B9 found in fortified foods and multivitamin, prenatal, and B complex supplements. Adult supplemental doses generally range from 680-1,360 mcg DFE. Supplemental doses of folic acid for an average of four months before reassessment may be considered in supporting folate levels. (2, 4, 8)
Dietary supplements containing the methylated form of folic acid, 5-MTHF, are also available. 5-MTHF may be more beneficial for those with MTHFR polymorphism(s), as it reduces the burden on the MTHFR enzyme to convert folate to its active form. (2)
Because human cells cannot synthesize folate, we depend on getting it through food or supplements. However, we know that the colonic microbiome contributes to human health in part through its ability to synthesize vitamins. Although the extent to which colonic folate synthesis influences human folate status is unclear, the microbiome does synthesize folate that enters systemic circulation (2). Therefore, implementing gut-supportive protocols that optimize digestion and a balanced microbiome may favor ideal folate levels. Supplements that may be utilized in this context include:
- Digestive enzymes
- Probiotics
- Fiber
- Demulcent and anti-inflammatory herbs: aloe vera, DGL, marshmallow
- Gut-supportive supplements: butyrate, glutamine, and zinc carnosine
For those taking a medication that may be affecting folate status, consider discussing alternative options with a healthcare provider. This may not be possible in all cases. You should never reduce or discontinue medication on your own without first consulting a doctor.
Summary
Folate deficiency is a common cause of megaloblastic anemia, characterized by decreased red blood cells with an abnormally large shape. Folate deficiency may contribute to undesirable anemia symptoms and carries the risk of other health complications. The good news is that folate deficiency and folate deficiency anemia have good outcomes when identified and addressed early through a healthy diet and supplementation. A functional medicine perspective provides a comprehensive approach that may help prevent folate deficiency recurrence and support better health outcomes.
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